Gracefully handle missing rules due to wrong PMD version

[adangel]

When using m2e + m2e-code-quality + pmd-eclipse-plugin, configuration of the project might fail, if the PMD versions don't match. E.g. the PMD version in the project might be newer than the one used by eclipse.

Example stack trace:

Sep. 27, 2018 2:01:59 NACHM. net.sourceforge.pmd.rules.RuleFactory buildRule
SCHWERWIEGEND: Error instantiating a rule
java.lang.ClassNotFoundException: net.sourceforge.pmd.lang.java.rule.basic.OverrideBothEqualsAndHashcodeRule cannot be found by net.sourceforge.pmd.eclipse.plugin_4.0.17.v20180801-1551
	at org.eclipse.osgi.internal.loader.BundleLoader.findClassInternal(BundleLoader.java:508)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:419)
	at org.eclipse.osgi.internal.loader.BundleLoader.findClass(BundleLoader.java:411)
	at org.eclipse.osgi.internal.loader.ModuleClassLoader.loadClass(ModuleClassLoader.java:150)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:499)
	at net.sourceforge.pmd.rules.RuleBuilder.build(RuleBuilder.java:179)
	at net.sourceforge.pmd.rules.RuleFactory.buildRule(RuleFactory.java:189)
	at net.sourceforge.pmd.RuleSetFactory.parseSingleRuleNode(RuleSetFactory.java:562)
	at net.sourceforge.pmd.RuleSetFactory.parseRuleNode(RuleSetFactory.java:461)
	at net.sourceforge.pmd.RuleSetFactory.parseRuleSetNode(RuleSetFactory.java:367)
	at net.sourceforge.pmd.RuleSetFactory.createRuleSet(RuleSetFactory.java:214)
	at net.sourceforge.pmd.RuleSetFactory.createRuleSet(RuleSetFactory.java:209)
	at net.sourceforge.pmd.RuleSetFactory.createRuleSets(RuleSetFactory.java:170)
	at net.sourceforge.pmd.RuleSetFactory.createRuleSets(RuleSetFactory.java:154)
	at net.sourceforge.pmd.eclipse.runtime.properties.impl.ProjectPropertiesManagerImpl.loadRuleSetFromProject(ProjectPropertiesManagerImpl.java:175)
	at net.sourceforge.pmd.eclipse.runtime.properties.impl.ProjectPropertiesManagerImpl.fillProjectProperties(ProjectPropertiesManagerImpl.java:246)
	at net.sourceforge.pmd.eclipse.runtime.properties.impl.ProjectPropertiesManagerImpl.loadProjectProperties(ProjectPropertiesManagerImpl.java:116)
	at net.sourceforge.pmd.eclipse.plugin.PMDPlugin.loadProjectProperties(PMDPlugin.java:510)
	at net.sourceforge.pmd.eclipse.runtime.cmd.ReviewCodeCmd.getProjectProperties(ReviewCodeCmd.java:442)
	at net.sourceforge.pmd.eclipse.runtime.cmd.ReviewCodeCmd.processResourceDelta(ReviewCodeCmd.java:616)
	at net.sourceforge.pmd.eclipse.runtime.cmd.ReviewCodeCmd.execute(ReviewCodeCmd.java:219)
	at net.sourceforge.pmd.eclipse.runtime.cmd.JobCommandProcessor$1.run(JobCommandProcessor.java:93)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:60)

Other example:

An internal error occurred during: "Updating Maven Project".
Unable to find referenced rule IdenticalCatchBranches; perhaps the rule name is mispelled?

[adangel]

Similar case: https://github.com/m2e-code-quality/m2e-code-quality/issues/213